When we're interpreting netflow data, we generally want packets-per-second and bits-per-second (bytes-per-second would also be acceptable but not ideal).
But Turnilo wants to sum up each within a given split window (1 minute / 5 minutes / 1 hour etc), so if you need absolute values or to cross-check with other sources of data, constant unit conversion is necessary.
I did file a FR upstream about this and was informed of the $MillisecondsInInterval config knob, but hadn't gotten around for asking to try it out on wmf_netflow until now :)